Traditionally, contact lens were developed and marketed for use on the exterior surface of the eye. The contact lens were initially all made from glass material, however, glass has been substantially replaced with synthetic plastic materials, particularly materials that minimize any reaction by the eye.
In 1989, the Russians disclosed a silicone intraocular contact lens. FIG. 27 shows an eye fitted with the Russian intraocular contact lens revealing its method of attachment in the eye. Specifically, the intraocular contact lens 200 includes a curved lens body 202 in contact with the natural crystalline eye lens 204. In the center of the curved lens body 202 extends a protrusion 206 defining an annular groove 208 with the curved lens body 202. The protrusion 206 is fitted through the iris 210 so that the inner circular edge 212 of the iris 210 is received within the annular groove 208.
In 1991, the Russians again disclosed a new silicone intraocular lens 300. FIG. 28 shows a transverse cross-sectional view of the intraocular lens having a curved body portion 302 with an annular protrusion 304. The annular protrusion 304 defines a substantially sharp circular edge 306. This particular lens has experienced some difficulties in use due to the substantially sharp circular edge 306 scraping against the inside surface of the iris repeatedly when the iris changes size causing pigment from the iris to be scraped from the iris.